Alfred thomas rapkin and frank cossor



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INDICATING THERMOMETER.

No. 483,365. Patented sept; 27, 1892.

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UNITED STATES PATENT OFFICE.

ALFRED THOMAS RAPKIN AND FRANK COSSOR, OF LONDON, ENGLAND;

SAID OOSSOR ASSIGNOR TO SAID RAPKIN.

lNDlCATlNG-THERMOMETER.

PECIFICATION forming part of Letters Patent No. 483,365, dated September 27, 1892. Application tied retmry 11, 1892. serai No. 421,088. (No model.)

To @ZZ whom it may concern.-

Beit known that we, ALFRED THOMAS RAP- KIN and FRANK OOSSOR, subjects of the Queen 0f Great Britain and Ireland, residing at London, England, have invented certain new and useful Improvements in Thermometers, ot`

which the following is a specilication.

This invention relates to improvements in thermometers, and has for its object to enable one reading to be readily compared with another or the mean or maximum temperature of one day to be compared with that of another.

In carrying out our invention and according to one arrangement we provide the thermometer with an additional independent tube that is parallel with and adjacent to the thermometentube and which we term an indicating-tube, which is sealed at both ends and contains any suitable liquid. Within such indicating-tube we place a movable indicator, which is advantageously composed of some magnetic substance, such as steel, so as to be capable of being moved up or down by means of a magnet applied from the outside. The indicating-tube is provided with a scale whose divisions are arranged to correspond with those of the thermometer scale. By shifting the movable indicator up or down within the indicating-tube said indicator can be brought to coincide wit-h the level of the mercury or the liquid of a thermometer or with the level of the indicator of an indicating-thermometer, which indicator can then be shifted into position for taking a fresh reading. When the next reading is taken, the ditterence between the temperature indicated by the indicator and that indicated by the level of the mercury or the liquid or of the thermometer-indicator can be quickly read off, and the difference in temperature between the two readings be thus readily ascertained.

If desired, we may employ several indicating-tubes instead of one, so that a table of the differences in temperature existing between several days can be kept and be compared.

The accompanying drawings illustrate various applications of our invention.

Figure l shows a Sixs self-indicating minimum and maximum thermometer provided with a single indicating-tube, and Fig. 2 is a cross-section thereof. Fig. 3 also shows a Sixs thermometer, but provided with two indicatingtubes. Fig. 4 shows a bent indicating-tube which may be used in place of the two indicating-tubes shown in Fig. 3. Fig. 5 shows an ordinary thermometer provided with a single indicating-tube.

In all the iigures like letters indicate similar parts.

Referring more particularly to Fig. l, ct a are the two limbs of the thermometer-tube, between which the independent and parallel indicating-tube b is situated, these tubes being retained in place upon the plate c by means of clips d or in any other suitable manner. c c are the minimum and maximum indicators, respectively, and f is the indicator of the tube l2. The plate c is provided with the ordinary Fahrenheit or other scale, the divisions thereof being prolonged, so as to enable the scale to be conveniently read oft from either the thermometer-tube or the indicatortube. e is at 20s,.while the indicator f, which was set when the previous reading was taken to the temperature then indicated by the minimum indicator c, is at 700. By comparing these two readings the difference in the minimum temperature existing between, say, twodays, is easily ascertained. In this instance it would be 70D-20S5O0.

In the arrangement shown by Fig. 3 the limbs of the thermometer-tube are formed wider apart, so as to permit of two independent and parallel indicating-tubes b b or the' bent independent indicating-tube h2, Fig. 4, being situated between said limbs, and thus enable both the maximum and minimum temperatures to be compared. This gure shows the thermometer-indicators c and e shifted into position for taking a fresh reading, while the indicators f and f are shown in the positions to which they have been set to show the previous maximum and minimum readings.

When the independent and parallel indidicating-tube is applied to an ordinary thermometer, as shown at Fig. 5, the dierence in temperature existing at certain fixed times can be compared. Thus it the temperature In this figure the minimum-indicator IOO indicated by the mercury or the liquid in the thermometer-tube g at, say, two oclock p. m.

ter-tube.

Ve do not claim anY indicating device in a glass tube and moved by the changes ot' temperature and set by a magnet. Neither do we claim an indicating device combined with a thermometer and capable ot' being set by hand. This, however, is liable to be moved accidentally or designedly.

We claim as our inventionl. The combination, with a thermometer, of an adjacent parallel and independent glass tube having an indicator therein that is Vnot iniiuenced by the changes of temperature, but is set in either direction by a magnet, substantially as specified.

2. The combination, With a thermometer having indicators that are moved by changes of temperature, of an adjacent parallel and independentrglass tube having an indicator therein that is not iniiuenced by the changes of temperature, but is set in either direction by a magnet, substantially as specified.

3. The combination, with a thermometer, of an adjacent parallel and independent glass tube having an indicator therein that is not influenced by the changes of temperature, but is set in either direction by a magnet, and a scale the divisions of which are common to both the thermometer-tube and the independent indicating-tube, substantially as specified.

4. The combination, with an indicatingthermometer having two connected parallel limbs a a and having indicators that are moved by changes of temperature, of an independent glass tube between the said limbs and adjacent and parallel thereto and having an indicator therein that is not iniuenced by changes of temperature, but is set in either direction by a magnet, and a scale the divisicns of which are common to both the thermometer-tube and the independent indicatingtube, substantially as specified.

In witness whereof We have hereunto signed our names in the presence of two subscribing witnesses. Y

ALFRED THOMAS RAPKIN. FRANK COSSOR. Witnesses:

I-I. AsHBY NoRRIs,

7 8 Fleet Street, Londo-n. JOSEPH LAKE,

17 Gracechurch Street, London, E. C'. 

